Synchronizing device



Jan- 5 1943- J. E. PEEK 2,307,334

'sYNcHRoNIzING DEVICE Fnvlied Maron 21, -1940 W/rMe-ss.- @sci -u 4 9 Patented, Een. 5, i@ ...e

narran stare This invention relates to a synchronizing device, particularly adapted to the synchronizing of prime movers the speed of one of Which may be manually varied and the speed of the other of which should be varied automatically to correspond. The invention is particularly adaptedl for the synchronizing of propeller driving-en gines in aircraft. 4

For the proper operation ofaircraft having a plurality of propellers, it is essential that the propellersbe underclose control so that the thrusts produced may be either equal or properly related to each other. In the case of an airplane having three propellers, for example, it is generally essential that theouter propellers be driven at the same rate, while the central propeller may be driven at either the same or some related rate, depending upon Whether or not it is of the same size and pitch as the others.

The general object of the present invention is to provide a simple synchronizing arrangement for the automatic control of the relative speeds of prime movers and specifically of such nature that the number of revolutions are under such close control that variations of the total number of revolutions beyond a particular amount is impossible.

The above object and other objects of the invention, particularly relating to details, will become apparent from the following description, read in conjunction with the accompanying drawing in which:

Figure l ls a diagrammatic View illustrating a preferred form of the synchronizing arrangement with the parts conventionalized and not to scale; and

Figure 2 is a fragmentary diagrammatic view illustrating a modincation.

Referring iirst to Figure 1, there is disclosed therein an internal combustion engine 2 driving a propellant and, through reduction gearing 6 and a clutch t, a spiral gear it. The speed of the engine 2 may be manually controlled by means of a' throttle i2 subject to manipulation by the operator. i The spiral gear l@ meshes with a plurality 'of elongated spiral gears i6, which are similarly connected for the control of another pair of engines 2t, arranged to drive propellers 2. Since the arrangements are identical, only one need be described in detail. Each spiral gear i6 ls splined to a shaft i8 so as to be movable axially along its shaft, which is parallel to the shaft of the spiral gear it. drives through reduction gearing 2t and a suit- An engine 2t I6. These connections have been conventional# ized in the gure, but it will' be understood that4 flexible;l shafting or the like may be provided. Since these connections need not transmita'ny appreciable power, it will be evident, that they may be readily run to a remote position 0f the spiral gear arrangement. The entire spiral gear assembly including clutches 8, 2B and 3i), may be quite small and may form a compact unit adjacent the operators position, for example, on an instrument panel. Each spiralgear i6 in-its axial movements adapted throughthe medium of a collar and pin connection to rock a lever 32, connected through' a link 35 to the throttle 36 of the corresponding engine 2G. Initial adjustments may beefiected by nuts 38 threaded on the link 34. A dash pot t@ is provided to stabilize theoperation and prevent hunting. Springs 0 and t2 normally tend to urge the spiral gear I6 to -a central position. It Will be evident that these springs may be 1ocated in some other part of the connections t.

eiect the same result. The springs maintain the gears in centrally meshed condition when the clutches are disengaged so that when the control mechanism is brought into operation variations are about said central positions.

The operation of the arrangement Will be readily apparent. The connections are so made that if, with the engine 2 running at a certain speed determined by manual. control of its throttle, one of the engines -20 varies from such speed, its corresponding gear it will tend to rotate faster or slower than the proper speed determined by the meshing of it with the controlling gear it. As a result of the presence of the spiral teeth, an end thrust will be set upto move the lever 32 and so adjust the throttle B of the engine it to cause it to 'speed up or slow down to synchronismwith' the engine 2. As indicated above, the arrangement does not require that the englnes operate at the same speed. If particular dlerent speed ratios are required,this is taken care of by different gear ratios in the reduction gear boxes 6 and A2li. It Will be evident in connection with this modification that the presence of reduction Agearing is essential, inasmuch as if it were not present a difference of one revolution would cause an excessive movement of the spiral gears relative to each other. It will be evident 'that the control of the two engines 2@ from the single gear il) may be eiiected without v the operation of one interfering with the other.

Under normal conditionsit will be clear that able clutch 2t connections it and t@ to the shaft 55 an equilibrium condition will be reached aided by suitable damping through the medium of the dash pots so that synchronism is accurately obtained. The total number of revolutions of the engine 20 cannot diier by more than a predetermined amount from a corresponding number of revolutions of the engine 2.

While there is illustrated one internal combustion engine controlling two others, obviously two internal combustion engines may be maintained in synchronism by using only one gear i6 in mesh with a spiral gear I0. Alternatively, a larger number may be controlled by duplication of the arrangement illustrated.

It is not necessary that the controlling gear i be driven from an internal combustion engine. Instead, it may be driven by some small prime mover, such as a small electric motor, the speed of which is subject to control. Thus engines such as those illustrated at may7 be be kept in synchronism with each other and with any suitable prime mover. The control is Vadapted not only for internal combustion engines, since it will be obvious that the lever 32 may well control a rheostat to adjust the speed of an electric motor or to adjust inlet of fluid to a steam or liquid turbine.

The principles of the invention may be embodied in other fashions, for example as illustrated in Figure 2, in which a shaft 48 corresponds to the shaft driven bythe controlling prime mover and has mounted on it a spur gear 46 corresponding to the gear l0 in determining the speed of operation. Meshing with the gear 46 is an elongated spur gear 50, which is internally threaded to serve as a nut upon the threaded por-tion 52 of a shaft 54 connected to the prime mover the speed of which is to be controlled. The gear 50 carries a collar which controls a lever 56, corresponding to lever 32. It will be evident here again that if the speed of the shaft 54 rises or falls with respect to the normal speed corresponding to that of shaft 48, a lengthwise movement of the gear 50 will result to effect control of the prime mover driving the shaft 54. If a fine thread is used at 52, reduction gearing such as 6 and 24 may be avoided, since the axial movements of a dash pot may also be avoided in such case,

' since the arrangement can be made of dead beat character.

In both of the arrangements illustrated, it is desirable for safety purposes to so arrange the mechanism that in the event of stoppage of any of the prime movers the gears may move entirely out of mesh or may become entirely disconnected from one of the driving shafts. In starting up the system, it is, of course, necessary that approximate synchronism of speeds be obtained before the various elements are thrown into connection by 'manipulation of the clutches.

It will be clear that the invention may be erf-- bodied in other modications Without departing from the scope of the invention as defined in the following claims.

What I claim and desire to protect by Letters Patent is:

1. In combination, a variable speed prime mover, a gear driven by said prime mover, a second prime mover, a second gear meshing with the rst gear and arranged to be driven by the second prime mover, clutching means between said second gear and said second prime mover, means mounting said gears for relative axial movement upon occurrence of diierences in their driving speeds. and means for varying the speed of said second prime mover responsive to said relative axial movement of the gears, and spring means for urging at least one of said gears toward a mean relationship of thel gears when said one gear is declutched.

2. In combination, a variable speed prime mover, a gearv driven by said prime mover, a second prime mover, a second gear meshing with the rst gear and arranged to be driven by the second prime mover, clutching means between one of said gears and its prime mover, means mounting said gears for relative axial movement upon occurrence of differences in their driving speeds, and means for varying the speed of said second prime mover responsive to said relative axial movement of the gears: and spring means for urging at least one of said gears toward a mean relationship of the gears when said one gear is declutched.

JESSE ELDON PEEK. 

